Optical cable is widely used as a communication medium in both public and private communication networks. Optical cable comprises glass or plastic fibers that are relatively fragile, and require strength members for protection from tensile stress during processing, installation, and servicing. It is known that excess tensile stress may cause the optical characteristics of the fibers to change, resulting in transmission loss. Accordingly, a variety of different strength system designs for optical cables have been proposed for the protection of the transmission integrity of the fibers contained therein.
Strength system designs typically include the use of rigid strength rods or flexible members made from materials such as steel, KEVLAR.RTM. (a registered trademark of E. I. du Pont de Nemours and Company), epoxy/aramid, epoxy/glass, etc. The rigid strength members may form the core of an optical cable, wherein the optical fibers are packaged into one or more plastic buffer tubes that are stranded around the strength member. Alternatively, fiber bundles or ribbons may be disposed in the central portion or core of the optical cable, wherein the strength members are disposed outside the core, typically embedded within the optical cable jacket.
An improved strength member which provides advantageous strength and flexibility characteristics has been developed by Lucent Technologies, Inc. The improved strength member comprises a strength tape that wraps around a core fiber bundle. The strength tape includes a plurality of strands that are woven together into a linear strength tape, as described in greater detail below.
However, there exist practical limits to the maximum length of the strength members utilized in an optical cable. Depending upon the type of strength members utilized, the maximum length of the strength members may be less than the desired length of the optical cable. The maximum length of the strength members may be limited by numerous factors such as material characteristics, fabrication techniques, size and weight considerations, etc.
One technique for extending the length of a strength member is to splice two strength members together so that the combined length is suitable for the particular optical fiber cable being manufactured. A strength member splice has to meet specific requirements in order to be an acceptable method for extending the length of the strength member. For instance, the splice may be required to meet predetermined benchmarks for strength, stiffness, aging, size, and outgassing. In addition, it is desirable to be able to splice strength members on-line during manufacture of the optical cable, and therefore, the method should take a minimum amount of time to complete, and be user friendly.
Therefore, a need exists in the industry for splicing techniques for strength members, such as strength tapes, wherein the physical length of the strength members is less than the desired length of the optical cable. Preferably, the splicing technique is compatible with the manufacturing process of the optical cable so that the splice can be made on-line.